Expression of GLUT1 in stratified squamous epithelia and oral carcinoma from humans and rats

Mitochondrial Activity Is Upregulated in Nonlesional Atopic Dermatitis and Amenable to Therapeutic Intervention

Previous work has shown increased expression of genes related to oxidative stress in nonlesional atopic dermatitis (ADNL) skin. Although mitochondria are key regulators of ROS production, their function in AD has never been investigated. Energy metabolism and the oxidative stress response were studied in keratinocytes (KCs) from patients with ADNL or healthy controls. Moreover, ADNL human epidermal equivalents were treated with tigecycline or MitoQ. We found that pyruvate and glucose were used as energy substrates by ADNL KCs. Increased mitochondrial oxidation of (very) long-chain fatty acids, associated with enhanced complexes I and II activities, was observed in ADNL KCs. Metabolomic analysis revealed increased tricarboxylic acid cycle turnover. Increased aerobic metabolism generated oxidative stress in ADNL KCs. ADNL human epidermal equivalents displayed increased mitochondrial function and an enhanced oxidative stress response compared with controls. Treatment of ADNL human epidermal equivalents with tigecycline or MitoQ largely corrected the AD profile, including high p-65 NF-κB, abnormal lamellar bodies, and cellular damage. Furthermore, we found that glycolysis supports but does not supersede mitochondrial metabolism in ADNL KCs. Thus, aerobic metabolism predominates in ADNL but leads to oxidative stress. Therefore, mitochondria could be a reservoir of potential therapeutic targets in atopic dermatitis.

The Role of Glucose Transporters in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a prevalent malignancy associated with a poor prognosis. The Warburg effect can be observed in OSCCs, with tumours requiring a robust glucose supply. Glucose transporters (GLUTs) and sodium-glucose co-transporters (SGLTs) are overexpressed in multiple malignancies, and are correlated with treatment resistance, clinical factors, and poor overall survival (OS). We conducted a systematic review to evaluate the differences in GLUT/SGLT expression between OSCC and normal oral keratinocytes (NOK), as well as their role in the pathophysiology and prognosis of OSCC. A total of 85 studies were included after screening 781 papers. GLUT-1 is regularly expressed in OSCC and was found to be overexpressed in comparison to NOK, with high expression correlated to tumour stage, treatment resistance, and poor prognosis. No clear association was found between GLUT-1 and tumour grade, metastasis, and fluorodeoxyglucose (FDG) uptake. GLUT-3 was less thoroughly studied but could be detected in most samples and is generally overexpressed compared to NOK. GLUT-3 negatively correlated with overall survival (OS), but there was insufficient data for correlations with other clinical factors. Expression of GLUT-2/GLUT-4/GLUT-8/GLUT-13/SGLT-1/SGLT-2 was only evaluated in a small number of studies with no significant differences detected. GLUTs 7 and 14 have never been evaluated in OSCC. In conclusion, the data demonstrates that GLUT-1 and GLUT-3 have a role in the pathophysiology of OSCC and represent valuable biomarkers to aid OSCC diagnosis and prognostication. Other GLUTs are comparatively understudied and should be further analysed because they may hold promise to improve patient care.

Evaluating the expression of GLUT-1 in oral leukoplakia

Aim:

The aim of the present study is to analyze the role of GLUT-1 in detection of early alterations occurring in oral leukoplakia. This study was to evaluate the expression of GLUT-1 in normal oral epithelium, the expression of GLUT-1 levels in the tissue samples of oral leukoplakia and to statistically compare the expression of GLUT-1 in normal epithelium and oral leukoplakia.

Materials and Methods:

The study sample comprised formalin-fixed and paraffin-embedded tissue specimens from 23 cases of histopathologically diagnosed oral leukoplakia and formalin-fixed paraffin-embedded tissue specimens from 10 cases of normal oral mucosa. Sections were mounted on glass slide coated with Aminopropyltriethoxysilane (APES; Sigma chemical co., USA) and processed for subsequent immunohistochemical study to demonstrate GLUT-1.

Results:

GLUT-1 expression in normal oral mucosa revealed weak positivity in all 10 cases (100%). The oral leukoplakia cases showed immunopositivity in all 23 cases (100%) of which 10 cases (39.14%) demonstrated focal positivity and 13 cases (60.86%) of diffuse positivity. The results were compared statistically using ANOVA test was significant at P = 0.002.

Conclusion:

The present study shows expression of GLUT-1 in leukoplakia may be used as a reliable marker to identify the high risk group for malignant transformation.

Expression of Glut-1 in Malignant Melanoma and Melanocytic Nevi: an Immunohistochemical Study of 400 Cases

The glucose transporter-1 (Glut-1) is a cell membrane glycoprotein involved in glucose uptake. An increased expression of Glut-1 is an important cell adaptation mechanism against hypoxia. An upregulation of Glut-1 can be found in several types of malignant tumors, which are able to reprogram their metabolism from oxidative phosphorylation to aerobic glycolysis (Warburg effect). However, the data regarding melanocytic lesions is equivocal. We performed comprehensive immunohistochemical analysis of the Glut-1 expression in 225 malignant melanomas (MM) and 175 benign nevi. Only the membranous expression of Glut-1 was regarded as positive. The expression of Glut-1 (the cut-off for positivity was determined as H-score 15) was found in 69/225 malignant melanomas. The number of positive cases and the H-score of Glut-1 increased where there was a higher Breslow thickness (p < 0.00001) when comparing pT1- pT4 MM groups. All benign nevi were classified as negative. In conclusion, the membranous expression of Glut-1 is a common feature of a malignant melanoma but this type of expression is very rare in benign melanocytic nevi. Our results suggest that the membranous expression of Glut-1 can be used as a surrogate marker in the assessing of the biological nature of benign and malignant melanocytic lesions. However, despite its high specificity, the sensitivity of this marker is relatively low. Moreover, due to the fact that the increased expression of Glut-1 correlates with a shorter survival period (10-year disease free survival, recurrence free survival and metastasis free survival and MFS), it can be used as a prognostically adverse factor.

Evaluation of Hypoxia Inducible Factor-1α and Glucose Transporter-1 Expression in Non Melanoma Skin Cancer: An Immunohistochemical Study

INTRODUCTION

Hypoxia Inducible Factor-1 (HIF-1) is a mediator enabling cell adaptation to hypoxia. It plays its role mainly through transcription of many target genes including Glucose Transporter-1 (GLUT-1) gene.

AIM

The present work aimed at evaluating the pattern and distribution of HIF-1α and GLUT-1 in each case and control.

MATERIALS AND METHODS

A case-control and retrospective study was conducted on archival blocks diagnosed from pathology department as, Basal Cell Carcinoma (BCC, 20 cases), cutaneous Squamous Cell Carcinoma (SCC, 20 cases) and 20 normal site-matched skin biopsies from age and gender-matched healthy subjects as a control. Evaluation of both HIF-1α and GLUT1 expression using standard immunohistochemical techniques was performed on cut sections from selected paraffin embedded blocks.

RESULTS

HIF-1α was expressed in 90%, 35% and 100% of normal skin, BCC and SCC tumour islands respectively. It was up regulated in both BCC and SCC compared with normal skin (p= 0.001, p<0.001 respectively). GLUT-1 was expressed in 100%, 70% and 100% of normal skin, BCC and SCC tumour islands respectively. It was down regulated in Non Melanoma Skin Cancer (NMSC) cases compared with normal skin (p=0.004). HIF-1α and GLUT-1 localization in tumour nests was central, peripheral or central and peripheral. Both HIF-1α and GLUT-1 showed variable expression in stroma, adnexa and inflammatory cells. No significant correlation was found between Histo (H) score or expression percentage values of HIF-1α and those of GLUT-1 in tumour islands or in overlying epidermis either in BCC or SCC.

CONCLUSION

HIF-1α may have a role in NMSC pathogenesis through adaptation to hypoxia which results from excessive proliferation. GLUT-1 down regulation in NMSC may be explained by its consumption by proliferating tumour cells. The expression of HIF-1α and GLUT-1 in normal epidermis, stromal and adnexal structures needs further research.

Expression of Glut-1 in Normal Endometrium and Endometrial Lesions: Analysis of 336 Cases

Background: Glucose transporter-1 (Glut-1) is a membrane glycoprotein that is, together with other glucose transporters, responsible for the regulation of glucose uptake. An increased expression of this protein seems to be a general feature of several malignant tumors that are able to reprogram their metabolism and switch from oxidative phosphorylation to aerobic glycolysis. Methods: We performed comprehensive immunohistochemical analysis of Glut-1 expression in 336 endometrial samples, including tumors, nontumor lesions, and normal tissues. Results: Expression of Glut-1 was found in 87% of endometrioid carcinomas (160/184 cases), 100% of serous carcinomas (29/29 cases), 100% of clear cell carcinomas (17/17 cases), 50% of polyps with atypical hyperplasia (8/16 cases), 12.5% of polyps with non-atypical hyperplasia (3/24 cases), 77% of hyperplasias with atypias (10/13 cases), 9% of hyperplasias without atypias (1/11 cases), 87% of secretory endometrium samples (13/15 cases), and in none of the nonsecretory endometrium samples (0/27 cases). In endometrioid carcinomas, Glut-1 was expressed in a marked geographical pattern. In nontumor lesions, its expression was more common in atypical hyperplasia and polyps with atypical hyperplasia compared with polyps with non-atypical hyperplasia and hyperplasias without atypia ( P = .00032). Conclusion: Our study confirms the high expression of Glut-1 not only in endometrioid carcinomas but also in other carcinomas of endometrium including clear cell and serous types. Glut-1 expression can be used as a surrogate marker in differential diagnosis between hyperplasia with and without atypia. Because of common Glut-1 expression in malignant tumors, therapeutic strategies influencing this protein or its signaling pathways can be beneficial.

A tentative model for (D)-glucose turnover in human saliva

OBJECTIVE

The aim of the present study is to propose a tentative model for d-glucose turnover in human saliva. The whole saliva and the saliva from parotid and submandibular/sublingual glands were collected by use of the Salivette™.

RESULTS

The saliva glucose concentration was measured by the hexokinase method, saliva bacteria glycolysis by use of d-[5-(3)H] glucose, and the saliva ATP content by the luciferase method. The concentration of glucose amounted to 43.9±6.3 (n=29), 197.5±17.3 (n=29), 104.0±12.4 (n=27) μM in whole saliva, parotid saliva and submandibular/sublingual saliva, respectively. The rate of d-glucose utilization by oral bacteria at a physiological concentration of d-glucose in saliva (50μM) was estimated at 0.047±0.003 (n=11) nmol/min per 10(6) bacteria. Unstimulated salivary d-glucose turnover rate, as calculated from the amount of glucose secreted in saliva which comes from parotid and submandibular and sublingual glands represented 214.6±19.1%/min. In order for salivary d-glucose production to match bacterial utilization of the hexose, the total number of oral bacteria was estimated at about 2.0×10(9) bacteria, in fair agreement with previously published data.

CONCLUSION

This study thus provides support for a tentative model for d-glucose turnover in human saliva.

Optical imaging of oral squamous cell carcinoma and cervical lymph node metastasis

BACKGROUND

In oral cancer surgery, intraoperative optical imaging could help the surgeon to determine adequate tumor-free margins.

METHODS

Tumor-specific near-infrared fluorescence agents targeting epidermal growth factor receptor (CW800 EGF) or glucose transporter system (CW800 2-DG) were administered to mice with tongue carcinoma and cervical lymph node metastases. Tumor growth was followed by bioluminescence imaging. Fluorescence signals were compared with a control group of healthy animals.

RESULTS

Significantly higher fluorescence was found in tongue tumors and cervical lymph node metastases compared with that in control animals. Fluorescence correlated with histopathology. Tumor-to-background ratio of CW800 EGF in the tongue was 13.8 (SD = 6.1) and in the lymph nodes 15.7 (SD = 8.8). For CW800 2-DG, the tumor-to-background ratio in the tongue was 4.6 (SD = 2.1) and in the lymph nodes 33.9 (SD = 18.4).

CONCLUSIONS

Optical imaging can be used to detect oral cancer and cervical lymph node metastases and could potentially improve complete surgical resection by real-time image-guided surgery.

Glucose transport in the equine hoof

REASONS FOR PERFORMING STUDY

Several conditions associated with laminitis in horses are also associated with insulin resistance, which represents the failure of glucose uptake via the insulin-responsive glucose transport proteins in certain tissues. Glucose starvation is a possible mechanism of laminitis, but glucose uptake mechanisms in the hoof are not well understood.

OBJECTIVES

To determine whether glucose uptake in equine lamellae is dependent on insulin, to characterise the glucose transport mechanism in lamellae from healthy horses and ponies, and to compare this with ponies with laminitis.

METHODS

Study 1 investigated the effects of insulin (300 µU/ml; acute and 24 h) and various concentrations of glucose up to 24 mmol/l, on 2-deoxy-D-[2,6-(3)H] glucose uptake in hoof lamellar explants in vitro. Study 2 measured the mRNA expression of GLUT1 and GLUT4 transport proteins by PCR analysis in coronary band and lamellar tissue from healthy horses and ponies, ponies with insulin-induced laminitis, and ponies suffering from chronic laminitis as a result of equine Cushing's syndrome.

RESULTS

Glucose uptake was not affected by insulin. Furthermore, the relationship between glucose concentration and glucose uptake was consistent with an insulin-independent glucose transport system. GLUT1 mRNA expression was strong in brain, coronary band and lamellar tissue, but was weak in skeletal muscle. Expression of GLUT4 mRNA was strong in skeletal muscle, but was either absent or barely detectable in coronary band and lamellar tissue.

CONCLUSIONS

The results do not support a glucose deprivation model for laminitis, in which glucose uptake in the hoof is impaired by reduced insulin sensitivity. Hoof lamellae rely on a GLUT1-mediated glucose transport system, and it is unlikely that GLUT4 proteins play a substantial role in this tissue.

POTENTIAL RELEVANCE

Laminitis associated with insulin resistance is unlikely to be due to impaired glucose uptake and subsequent glucose deprivation in lamellae.

High glucose inhibits human epidermal keratinocyte proliferation for cellular studies on diabetes mellitus

In order to more clarify the delayed wound healing in diabetes mellitus, we cultured the human epidermal keratinocytes in both 6 mM (control group) and 12 mM glucose (high-glucose group) of "complete" MCDB 153 medium. Hyperglycaemia slowed the rate of their proliferation and inhibited their DNA synthesis and the production of total proteins. By 1 month after primary seeding in high-glucose group, the cells ceased their proliferation, whereas the cells in control group grew for more than 40 days. Mean population doublings in high-glucose group was 5.27 (vs. 7.25 in control, P = 0.001), and mean population doubling time during 1 month in high glucose group was 5.43 days (vs. 3.65 days in control, P = 0.02). They indicate that prolonged exposure to high glucose decreases the replicative life span of human epidermal keratinocytes in vitro. Furthermore, analysis of fatty acid contents in membrane phospholipids with thin-layer and gas chromatography showed no difference between the cultured keratinocytes in both conditions. Immunocytochemical staining of glucose transporter 1 shows that 28.1% of cells in high-glucose group were almost twice positive of those in control group (13.2%, P = 0.008). The mechanism of the ill effects of high glucose on epidermal keratinocytes is not so far clear, but it indicates the possibility of any direct effect of hyperglycaemia on glucose metabolism without changing lipid metabolism on cell membrane. The high-glucose group presented in this report can be available as an in vitro valuable study model of skin epidermal condition on diabetes mellitus.

Expression of Glucose Transporter-1 in Taiwanese Patients with Breast Carcinoma—A Preliminary Report

Malignant cells show increased glucose uptake in vitro and in vivo. High expression of the glucose transporter-1 gene (GLUT1) has been found in many human tumor tissues. The aim of this study was to investigate the correlation between GLUT1 expression in breast carcinomas of Taiwanese patients and clinical prognostic parameters. Twenty-eight (71.8%) of the 39 breast carcinomas analyzed showed positive GLUT1 expression with different intensities: 1+, 19 cases (48.7%); 2+, 6 cases (15.4%), 3+, 3 cases (7.7%). No significant correlation was seen between GLUT1 expression and clinical prognostic parameters such as tumor size (p = 0.085), age (p = 0.4528), axillary lymph node metastasis (p = 0.9562), nuclear grade (p = 0.6895), estrogen receptor-positive (p = 1.0000), and progesterone receptor-positive (p = 0.9689).

The differential expression of VEGF, VEGFR-2, and GLUT-1 proteins in disease subtypes of systemic sclerosis

Our aim was to evaluate (a) whether there is differential expression of the endothelial regulator vascular endothelial growth factor (VEGF), its receptor (VEGFR-2), and the hypoxia-associated glucose transporter molecule, GLUT-1, in skin biopsies from different disease subtypes of systemic sclerosis (SSc) and (b) whether they associate with dermal calcinosis, a significant complication of SSc. Skin punch biopsies were taken from the forearms of 66 SSc patients including 18 with limited cutaneous disease without calcinosis (lcSSc), 23 with calcinosis (lcSSc/cal), and 25 with diffuse cutaneous disease (dcSSc) and from 12 healthy control subjects. The histological appearance of the skin was graded as G0 (normal), G1 (dermal edema), or G2 or G3 (increasing fibrotic changes). Immunohistochemistry was performed with antibodies to VEGF, VEGFR-2, and GLUT-1. Staining was assessed in the epidermis, microvessels, and fibroblasts. The Kruskal-Wallis 1-way analysis of variance was used to compare the data between disease groups. VEGF protein was located in the epidermis and in dermal endothelial cells, pericytes, fibroblasts, and inflammatory cells. In dcSSc only, there was a significant increase in VEGF staining intensity in the keratinocytes and pericytes and the lowest percentage of microvessels with VEGF-positive endothelial cells. GLUT-1 protein was located in the epidermis, erythrocytes, and perineurium. In both lcSSc/cal and dcSSC, but not lcSSc, there were significant increases in GLUT-1 staining intensity of keratinocytes. We propose that in patients with dcSSc, there is a net increase in unbound VEGF in skin that may account for the raised levels of VEGF in serum reported by others. Increased GLUT-1 expression in lcSSc/cal and dcSSc indicates that hypoxia is an associated factor.

GLUT1 is highly expressed in cementoblasts but not in osteoblasts

Cementum is a specialized mineralized tissue covering root surface of the tooth. Although the tissue's composition resembles bone, there are distinct structural and functional differences between the two mineralized tissues. In this study, the genes that are differentially expressed in putative cementoblasts (human cementum-derived cells [HCDCs]) compared with preosteoblastic cells (human bone marrow stromal cells [BMSCs]) were screened by two independent microarray systems, and some of the selected genes were further analyzed by quantitative real-time RT-PCR. The gene encoding glucose transporter 1 [GLUT1], which showed the greatest difference between the two groups by the latter analysis, was subjected to further analyses. High levels of the GLUT1 protein in HCDCs, but not in BMSCs, were detected by Western blotting and immunocytochemistry. Furthermore, intense immunoreactivities for GLUT1 were observed in cementoblasts and cementocytes but not in osteoblasts or osteocytes in human periodontal tissues. These results indicate that GLUT1 may play a role in cementogenesis and could serve as a biomarker to differentiate between cells of cementoblastic and osteoblastic lineage.

Ex vivo produced human conjunctiva and oral mucosa equivalents grown in a serum-free culture system

PURPOSE

We sought to develop full-thickness ex vivo produced human conjunctiva and oral mucosa equivalents using a serum-free culture system without a feeder layer and to compare conjunctiva and oral mucosa equivalents to assess their suitability as graft materials for eyelid reconstruction.

MATERIALS AND METHODS

Human conjunctival and oral mucosal keratinocytes were cultured, expanded, and seeded onto AlloDerm (LifeCell Corp, Branchburg, NJ), a cadaveric, acellular dermis, to produce ex vivo produced full-thickness mucosa equivalents. Histology of equivalents and their expression of immunoreactive Ki-67, a proliferation marker, and GLUT1, a membrane antigen seen in barrier tissues, were examined at 4, 11, and 18 days after seeding onto AlloDerm.

RESULTS

Progressive epithelial stratification was observed on day 4, 11, and 18 conjunctiva and oral mucosa equivalents. Ki-67 immunoreactivity progressively increased with cultured time in both types of equivalent, indicating the continued presence of actively proliferating cells. GLUT1 immunoreactivity, concentrated in the basal keratinocytes of stratified epithelia of both types of equivalents, mimicked native tissue and indicated a high glycolytic state of the basal cells.

CONCLUSIONS

Conjunctival and oral mucosal equivalents are similar to native tissue and demonstrate high proliferative and glycolytic states. Due to the similarity to conjunctiva, oral mucosal equivalents may be useful for eyelid reconstruction. Their advantages for surgical reconstruction include 1) ease of obtaining autogenous oral epithelium for expansion in vitro without the possibility of contaminating cellular- or serum-borne biologic agents, 2) growth of intact, confluent epithelia on rigid, transplantable human allogeneic dermis that may be surgically transplanted, and 3) reduced donor site morbidity and surgical time.

Diagnostic value of GLUT-1 immunoreactivity to distinguish benign from malignant cystic squamous lesions of the head and neck in fine-needle aspiration biopsy material

The distinction of cystic squamous-cell carcinoma (SCC) from benign cystic squamous lesions (BCSLs) of the head and neck can be problematic on fine-needle aspiration biopsy (FNAB) material, particularly when BCSLs display epithelial reactive atypia or when SCC is well differentiated. Glucose transporter 1 (GLUT-1), a facilitative cell surface glucose transport protein, is aberrantly expressed in many cancers including oral and hypopharyngeal SCC. We evaluated the expression of GLUT-1 by immunochemistry on FNAB material to determine its value in distinguishing cystic SCC from BCSL of the head and neck. A 5-yr retrospective review of all head and neck cystic squamous lesions having FNAB specimens with cell block material, radiological studies, and histological confirmation was performed at our institution. Cell block material from 24 cystic squamous lesions, including 8 (33%) BCSL (7 branchial cleft cysts and 1 thyroglossal duct cyst[TDC]) and 16 (67%) metastatic SCCs with cystic/liquefactive degeneration, was retrieved and immunostained with anti-GLUT-1. GLUT-1 expression was considered positive when at least 10% of squamous cells exhibited distinct cell membrane reactivity. Positive GLUT-1 immunostaining was detected in all 16 SCCs and in none of the 8 BCSLs. In the carcinoma cases, the majority of malignant cells exhibited GLUT-1 reactivity; only a minor population of well-differentiated SCC cells displaying keratinization and arranged as squamous pearls did not express GLUT-1. GLUT-1 expression in cell block material can help to distinguish cystic SCCs from BCSLs of the head and neck. In conjunction with clinical and radiological correlation, GLUT-1 immunoreactivity can be an important diagnostic aid when the cytological findings are ambiguous.

GLUT1 messenger RNA and protein induction relates to the malignant transformation of cervical cancer

We studied whether induction of glucose transporters (GLUTs) 1 to 4 correlates with human papillomavirus (HPV)-dependent malignant transformation of cervical epithelium. Tissue samples of cervical intraepithelial neoplasia (CIN; grades 1 to 3), invasive carcinomas, and lymph node metastasis were examined. HPV typing was performed. Tissue sections were immunostained with GLUT1 to GLUT4 antibodies. Messenger RNA (mRNA) in situ hybridization confirmed GLUT1 protein expression. Weak expression of GLUT1 was found in nondysplastic HPV-positive and HPV-negative epithelium; significant expression was observed in preneoplastic lesions, correlating with the degree of dysplasia. In CIN 3 high-risk HPV lesions, cervical cancer, and metastasis, GLUT1 was expressed at highest levels with a strong correlation of GLUT1 mRNA and protein expression. Immunostains for GLUT2 to GLUT4 were negative. Cervical tumor cells respond to enhanced glucose utilization by up-regulation of GLUT1. The strong induction of GLUT1 mRNA and protein in HPV-positive CIN 3 lesions suggests GLUT1 overexpression as an early event in cervical neoplasia. GLUT1 is potentially relevant as a diagnostic tool and glucose metabolism as a therapeutic target in cervical cancer.

Caveolae, caveolin and cav-p60 in smooth muscle and renin-producing cells in the rat kidney

AIMS

In vascular smooth muscle cells caveolae are important for signalling mechanisms regulating vascular contraction. In smooth muscle layer of the renal afferent arteriole juxtaglomerular cells (JG cells) are non-contractile renin producing cells that have the capacity to change their phenotype into smooth muscle cells and back again by metaplastic transformation. Signalling mechanisms in JG cells are not fully understood and we therefore investigated if caveolae were present, and thereby could be involved as integrators of cellular signalling in both of these phenotypes of smooth muscle cells.

METHODS

Using electron microscopy we compared the number of caveolae in JG cells and smooth muscle cells in the afferent arteriole of the rat kidney. The expression of caveolin and cav-p60 was examined using a combination of immunogold electron microscopy and immunofluorescence microscopy.

RESULTS

We found that JG cells have sixfold less caveolae per cell surface sectional length than smooth muscle cells. The expression of cavolin-1 and cav-p60 correlated with the number of caveolae. An examination of the general distribution of caveolae, cav-p60 and caveolins in the rat kidney showed that cav-p60, like caveolin-1, is a specific maker of caveolae.

CONCLUSION

The number of caveolae in JG cells is very low, and this makes it unlikely that caveolae are of major importance for the renin secretion specific for JG cells.

Expression of glucose transporter-1 in cervical cancer and its precursors

OBJECTIVE

Increased glucose uptake and utilization is a known phenomenon exhibited by malignant cells. Overexpression of the glucose transporter protein family is thought to be the principal mechanism by which these cells achieve up-regulation. Our purpose is to determine glucose transporter-1 (GLUT 1) expression in squamous carcinoma of the cervix and precursor lesions.

METHODS

Archival histologic sections were obtained from 31 cases of invasive squamous cell carcinoma (SCC) of the uterine cervix, 15 cases of high-grade cervical intraepithelial neoplasia, 5 cases of low-grade, and 9 normal cervices. Immunohistochemistry for GLUT 1 protein was performed using polyclonal GLUT 1 antibody (Dako, Carpinteria, CA) and the labeled streptavidin-biotin procedure.

RESULTS

Compared to the internal control, the pattern of staining varied from weak (1+) to strong (3+) reactions. In normal cervix, 1+ GLUT 1 staining was seen in the basal cells of the squamous epithelium. All 31 (100%) cases of SCC were positive for GLUT 1. Positive reactions seemed more intense in tumor cells that were farther away from the stromal blood supply. There was a correlation between intensity of reaction for GLUT 1 and histologic grade of tumor (P = 0.0027) and with progression from normal or dysplastic lesions to invasive cancer (P = 0.0001). Intensity was a predictor of the presence of poorly differentiated tumor type. Low-grade CIN staining was seen in less than one-third of the epithelium, while in high-grade lesions the reaction was present in over one-half of the epithelium.

CONCLUSIONS

GLUT 1 is overexpressed in cervical carcinoma. The process appears to be related to grade of tumor but not to the progression from preneoplastic lesions. The results suggest that GLUT 1 overexpression is a late phenomenon in cellular transformation. Furthermore, the possible relation of expression to tumor blood supply suggests that the malignant cells may have an adaptive environmental ability to compensate for a compromised microenvironment.

Gene expression of GLUT isoforms and VHL in oral squamous cell carcinoma

In human oral squamous cell carcinoma (OSCC) cell lines, we detected atypical mRNA expression of GLUT2 and/or GLUT4 in addition to enhanced expression of GLUT1 mRNA using RT-PCR. In semi-quantitative reverse transcription-polymerase chain reaction analysis of mRNA expression in OSCC cell lines, we found an inverse relationship between mRNA expression of von Hippel-Lindau (VHL) and that of GLUT1, with no apparent influence on the expression of other GLUTs. These findings suggest that the reduction of VHL may play a critical role in glucose uptake of OSCC cell lines, with enhancement of GLUT1 expression.

Characterization of glucose transport system in keratinocytes: insulin and IGF-1 differentially affect specific transporters

Skin is one of the major tissues displaying chronic diabetic complications. We have studied glucose transport following stimulation with insulin and IGF-1 in cultured mouse keratinocytes. In proliferating cells, acute stimulation with insulin and IGF-1 increased glucose uptake. Insulin translocated glucose transporters 1 and 5, whereas IGF-1 translocated glucose transporters 2 and 3. With differentiation, glucose transporter 3 expression increased and the expression of glucose transporters 1, 2, and 5 decreased. No increase in glucose uptake was observed, however, following stimulation with either hormone. These results indicate that insulin and IGF-1 differentially regulate glucose uptake as well as expression and translocation of specific transporters in skin keratinocytes.

Carrier-mediated transport systems for glucose in mucosal cells of the human oral cavity

The in vitro uptake study was performed using the isolated cells of human oral mucosa, buccal and the dorsum of the tongue, to investigate the mechanisms of glucose uptake. The uptake of D-glucose was much larger in cells of the dorsum of the tongue than in buccal cells and was inhibited more extensively by 2-deoxy-D-glucose, a substrate of facilitative glucose transporters, than by alpha-methyl-D-glucoside, a specific substrate of SGLT1, suggesting the larger contribution of a facilitative transporter than Na(+)/glucose cotransporter. Furthermore, from the results of inhibition studies by several sugar analogues including maltose and D-mannose, GLUT1 and/or GLUT3 were suggested to take part in the glucose uptake by oral mucosa. Therefore, we have attempted to confirm the expression of glucose transporters on the oral mucosa by employing Western blotting. As a result, it was suggested that SGLT1, GLUT1, GLUT2, and GLUT3 are expressed in the epithelial cells of human oral mucosa.